1. Field of the invention
The present invention relates to an apparatus for creating a multi-length plastic tube for use in a water filter and more particularly, to the use of the multi-length plastic tube section in EDM (Electric Discharge Machining) apparatus water filters.
2. Description of the related art
Electric Discharge Machining systems utilizes water to cool and/or transport metal and other debris or shavings created during the machining of a workpiece. In most EDM machines, there is a pumping system that takes water, especially in a closed loop system, applies it to the working area to cool the surroundings and pick up debris and heat, and remove them from the area. The water then flows through a filter assembly to clean the water of such shavings and debris. Such filtered water is then available for reuse.
A problem in the art is that with current EDM filters having metal type cylindrical cores, there is a possibility of corrosion of such metal cores. The water normally utilized in EDM machining is de-ionized to maintain a substantially non-conductive property. As the filter, with an iron core, is utilized, interaction may be created between the metal shavings and debris with the metal center core, to cause corrosion thereof. Such corrosion of the metal core alters the water, making it somewhat conductive, thereby making the EDM process less efficient. In some EDM applications where higher precision machining is necessary, such corrosion problems and corresponding reduction of EDM efficiency is an important concern.
Different attempts have been made to combat this corrosion problem such as plating the iron core with certain non-corrosive ingredients, which becomes expensive or labor intensive. Further solutions of the problem include the use of creating plastic cores and plastic end-caps.
The use of plastic extruding technology has been tested but to date it has been impossible to obtain a wall thickness heavy enough to withstand the fluid hydraulic pressure seen by the EDM filter assembly during use.
Although the initial operating pressure of the typical water pumping system in EDM machines is approximately 18-20 PSI, as the filter material becomes saturated with debris, fluid pressures have been observed of up to 85-95 PSI. Furthermore, the current extruded plastic cores, when cut perpendicular to their longitudinal length, loses strength because of insufficient strength between core openings.
A problem with production of injection molded, plastic filter cores is the inability to vary the length of a plastic core unit on the fly. For creating injection molded plastic cores, each different length of the plastic core needs a different mold. Huge costs would thereby be created by making molds for the different size cores needed to satisfy all of the requirement of the different size EDM filter assemblies currently available.
The present invention solves the particular problem of eliminating the need for different sizes of injection molds for plastic filter cores and column systems.